System information

Troubleshooting Novell IPX 8-165
Novell IPX: Intermittent Connectivity
Enhanced IGRP and Active/Passive Modes
An Enhanced IGRP router can be in either Passive or Active mode. A router is said to be passive for
a network when it has an established path to the network in its routing table. The route is in Active
state when a router is undergoing a route recomputation. If there are always feasible successors, a
route never has to go into Active state and avoids a route recomputation.
If the Enhanced IGRP router loses the connection to a network, it becomes active for that network.
The router sends out queries to all its neighbors in order to find a new route. The router remains in
Active mode until it has either received replies from all its neighbors or until the active timer, which
determines the maximum period of time a router will stay active, has expired.
If the router receives a reply from each of its neighbors, it computes the new next hop to the network
and becomes passive for that network. However, if the active timer expires, the router removes any
neighbors that did not reply from its neighbor table, again enters Active mode, and issues a
“Stuck-in-Active” message to the console.
Novell IPX: Intermittent Connectivity
Symptom: Connectivity between clients and servers is intermittent. Clients might be able to connect
some of the time, but at other times no connectivity to certain servers or networks is possible.
Table 8-12 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table 8-12 Novell IPX: Intermittent Connectivity
Flapping route
Step 1 Check for a flapping serial route (caused by heavy traffic load) by using
the show interfaces privileged exec command. Flapping is a routing
problem where an advertised route between two nodes alternates (flaps)
back and forth between two paths due to a network problem that causes
intermittent interface failures. You might have a flapping route if there are
large numbers of resets and carrier transitions.
Step 2 If there is a flapping route, queries and replies might not be forwarded
reliably. Route flapping caused by heavy traffic on a serial link can cause
queries and replies to be lost, resulting in the active timer timing out.
Take steps to reduce traffic on the link or to increase the bandwidth of the
link.
For more information about troubleshooting serial lines, refer to Chapter
3, “Troubleshooting Serial Line Problems.”
Possible Problem Solution
SAP timer mismatch
Step 1 Use the show running-config privileged exec command to view the router
configuration. Look for ipx sap-interval interface configuration command
entries.
Step 2 On LAN interfaces, it is recommended that you use the default SAP
interval of 1 minute because the interval on servers cannot be changed. To
restore the default value, you can use the no ipx sap-interval command.
On serial interfaces, make sure that whatever interval you configure is the
same on both sides of the serial link. Use the ipx sap-interval interface
configuration command to change the SAP interval.
Possible Problem Solution